All Questions

1
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0answers
24 views
+50

Why do we observe two separate rings for signal and idler in type-II non-collinear SPDC (Spontaneous Parametric Down Conversion) Process?

I understand that in SPDC process (here: type-I, non-collinear), there is conservation between the pump, signal and idler photons in terms of energy and momentum, as a result of which the signal and ...
0
votes
1answer
38 views
+50

Order of magnitude radiation measures conversion?

Standard unit of ionizing radiation dose is Sievert. I can get a rough idea of how dangerous absorbing various amounts is from https://xkcd.com/radiation/ and other sources. There are many other ...
1
vote
0answers
44 views
+50

Does freezing point depression also affect the speed at which something melts?

If you have a pure water frozen, then it should begin to melt if you apply 33°F air to it. If you have impure water that's frozen, it's melting temperature might have dropped to 30°F. If you apply ...
2
votes
1answer
53 views
+50

How much air could an activated charcoal bag or baking soda box actually purify / deodorize?

Someone I know recently bought a set of small stylish and expensive cloth bags (roughly paperback book sized) filled with activated bamboo charcoal, that you place in a room and it purportedly ...
3
votes
0answers
53 views
+100

What is the meaning of the diamagnetic current in linear response theory?

When we consider the response of a quantum lattice model with Hamiltonian $H=H_{kin}+H_{int}$ to an applied vector potential $\mathbf{A}(\mathbf{r},t)$ we obtain the current operator $\mathbf{j}(\...
1
vote
0answers
45 views
+50

Virasoro algebra commutation (part 2)

This was a sub-question in my previous post that I ask separately now. In Introduction to Conformal Field Theory by Blumenhagen and Plauschinn (springer link) the Virasoro algebra is introduced the ...
1
vote
0answers
77 views
+50

Uniqueness constraint(s) on spacetime

What additional constraint(s), if any, must be used with the gravitational field equations $$R_{\mu\nu}=\kappa \left( T_{\mu\nu}-\frac{1}{2}Tg_{\mu\nu} \right)$$ to uniquely determine the Christoffel ...
1
vote
0answers
102 views
+50

Is this analysis contradictory with the $2$'nd measurment?

Summary and Motivation "The below idea is about making a mathematical statement on system $2$ which induces a measurement on system $1$ while $1+2$ obeys unitary evolution." Basically, I'm modelling ...